The present invention relates to a device for chilling fresh fruit and other fresh food products and, more particularly, to an improved under-counter fruit chiller utilizing a Peltier effect thermoelectric device.
Thermoelectric devices operating in accordance with the well know Peltier effect have been used as cooling/heating devices for many years. Such a thermoelectric device comprises an array of semiconductor couples connected electrically in series and thermally in parallel. The semiconductor couples are sandwiched between metalized ceramic substrates. When DC electric current is applied in series to the thermoelectric device, it acts as a heat pump with heat being absorbed on the cold side, thereby cooling it, while heat is dissipated at the other side. Reversing the current causes the direction of heat flow to be reversed. Attaching a heat sink and a cold sink to the respective hot and cold sides may enhance the efficiency of the thermoelectric device.
Peltier effect devices have long been used to provide coolers and/or heaters for keeping foods fresh or for warming foods for serving. It has also been found and is well known to use forced-air convection to aid in heat transfer. A small electric fan is typically used to circulate air past the cold sink and into and through a container for the food, while another fan moves ambient outside air across the heat sink to dissipate heat from it.
Although chillers for fresh fruit and other perishable food products are well known in the art, the market success of such devices has been limited. There appear to be a number of reasons for this lack of market success. One is the cost and heat transfer efficiency of the solid state thermoelectric modules. In addition, the need to provide circulation of cool air to attain the greatest cooling efficiency has led to complex duct systems which add substantially to the cost of the containers, typically made of molded plastic materials. A long air circulation duct system also results in heat loss and pressure drop, both of which decrease the efficiency or add to the product cost. Another issue with prior fruit chillers is the utilization of counter space. Limited counter space availability in current homes can restrict the purchase of additional counter top appliances. The fruit chiller of the current invention utilizes kitchen space otherwise underutilized.
In accordance with the present invention, a chiller for fresh fruit or other perishable food products utilizes a construction which optimizes a cooling air flow and thus heat transfer efficiency with a container construction that is less expensive to manufacture and permitting the use of a relatively smaller thermoelectric module. Thermoelectric modules of increased efficiency, such as disclosed in U.S. Pat. No. 5,448,109, are particularly suitable for use in the fruit chiller of the subject invention.
In one overall embodiment, the food chiller of the present invention is mounted under a cabinet or other overhanging horizontal surface and comprises a housing for mounting a Peltier effect thermoelectric module sandwiched between a cold sink and an opposite heat sink. The housing also defines a downward facing duct system that includes a cool air supply duct in heat transfer communication with the cold sink, a return air duct, and a cool air circulation fan in the cooling duct system to circulate air therethrough.
A food container portion is adjacent the housing and contains enclosing sidewalls and is openable from the housing for retrieval of the food. The food container portion has therein a plurality of inlet and outlet holes in a wall that completes the duct system.
In one embodiment the food container is slidably attached to the housing. Sliding the food container relative to the housing allows access to the food contained therein.
In another embodiment the food container is pivotally mounted to the housing. Pivoting the food container away from the housing allows access to the food contained therein.
In another overall embodiment, the food chiller of the present invention is located on a counter surface in the corner of two intersecting walls and comprises a housing for mounting a Peltier effect thermoelectric module sandwiched between a cold sink and an opposite heat sink. The housing also defines a lateral facing duct system that includes a cool air supply duct in heat transfer communication with the cold sink, a return air duct, and a cool air circulation fan in the cooling duct system to circulate air therethrough.
A food container portion is adjacent the housing and contains enclosing sidewalls and is openable from the housing for retrieval of the food. The food container portion has therein a plurality of inlet and outlet holes in a wall that completes the duct system.
The food container portion is normally such that cooling air is continuously recirculated. In one embodiment, however, an outside ambient air supply conduit communicates with the cooling duct system and includes a metering device to admit a controlled flow of outside air to assist in purging the cooling duct system of ethylene gas and other ripening by-products of fruit. The metering device may comprise a small diameter tube connected to the duct system upstream of the fan.
To help maintain the interior temperature of the container, a removable insulating sleeve may be inserted into the container. The sleeve is shaped to conform to the interior of the enclosing sidewall. The removable cover may also be provided with an insulating liner.
Various arrangements of partitions may be placed within the container to divide the container into different temperature zones by varying the flow of cooling air through the zones. Such partitions may be vertically disposed to extend upwardly from the container bottom wall or may be horizontally disposed and attached, for example, to a central tower or to the container sidewall.